Pressure-sensitive adhesive composition for optical films and pressure-sensitive adhesion type optical film

A pressure-sensitive adhesive composition, comprising:

• (I) an acrylic diblock copolymer of formula (1):
• A-B (1),
• wherein:
• A is a methacrylic acid alkyl ester polymer block;
• and
• B is an acrylic acid alkyl ester polymer block,
• wherein the content of the polymer block B is 10 to 55% by mass, based on a total mass of the acrylic diblock copolymer (I), and
• wherein the acrylic diblock copolymer (I) has a weight-average molecular weight (Mw) in a range from 9,000 to 300,000, and a molecular weight distribution (Mw/Mn) in a range from 1.0 to 1.5;
• and
• (II) an acrylic triblock copolymer of formula (2):
• C1-D-C2 (2),
• wherein:
• C1 and C2 are each independently a methacrylic acid alkyl ester polymer block having a glass transition temperature of not lower than 100° C.;
• and
• D is an acrylic acid alkyl ester polymer block having a glass transition temperature of not higher than −20° C.,
• wherein the content of the polymer block D is 82 to 95% by mass, based on a total mass of the acrylic triblock copolymer (II), and
• wherein the acrylic triblock copolymer (I) has a weight-average molecular weight (Mw) in a range from 50,000 to 300,000, and a molecular weight distribution (Mw/Mn) in a range from 1.0 to 1.5,
• wherein a mass ratio of the acrylic diblock copolymer (I) to the acrylic triblock copolymer (II), (I)/(II), is in the range of 70/30 to 41/59.